It is well established that hair can be curled utilizing heat resulting from the contact of moistened exothermic materials with aluminum foil.
By way of example, hair curling packages in accordance with U.S. Pat. No. 3,545,457 are sealed envelopes with are sufficiently flexible to be formed into rolls about which tresses may be wound. Each envelope consists of outer, water repellant layers or sides with an inner, aluminum foil layer bonded to each of them and contains an absorbent layer carrying exothermic material. The exothermic material when the absorbent layer is properly wetted and the material is in contact with the foil is capable of providing heating intervals of several minutes duration with the exterior surfaces of the envelope at a temperature in the approximate range of 80.degree. F. to 140.degree. F. Each envelope has a multiplicity of apertures of pin prick dimensions distributed uniformly over its surfaces for the entry of sufficient water to wet the absorbent layer to the appropriate extent.
Such packages, when the absorbent layer was appropriately wetted and the package in the form of a roll and with tresses wound about it, enabled the tresses to be efficiently curled both by professionals and by individuals curling their own hair. Such packages are, however, relatively expensive to manufacture and the flexibility of the envelopes is restricted by the absorbent layers. In addition some difficulty is often experienced, at least initially, in moistening the absorbent layer to the appropriate extent and the exothermic material is relatively free within the envelope.